Hospital logistics can significantly benefit from autonomous robotic technologies capable of alleviating personnel workload, reducing operational costs, and streamlining internal workflows. This paper introduces HOSBOT (HOSpital roBOT), a modular and cost-effective robotic system designed to enhance hospital logistics and workflow management through autonomous missions and real-time monitoring of transported items. HOSBOT combines a commercially available autonomous mobile robot with a customisable non-motorised cart, the SmartRack, which accommodates standalone, sensorised SmartBoxes equipped with Radio Frequency IDentification technology. This paper describes the overall design of HOSBOT, including its mechanical, electrical, and software interfaces. The system has been validated in three pilot experiments in real hospital environments across Europe, demonstrating good levels of acceptability, usability and efficacy. This innovative robotic solution highlights the potential for scalable integration of autonomous mobile robots in healthcare and other indoor logistics settings.

Rotary Series Elastic Actuators (SEAs) are largely adopted to safely and accurately modulate interaction torques when robots operate in close contact with humans. Torque control is often based on a cascade scheme including PI regulators for a velocity controller nested in a torque controller. This solution is simple, robust and can potentially guarantee coupled stability. A high-level impedance control loop is also commonly added to regulate the behavior of the interaction port as a desired virtual viscoelastic body. In the present work, passivity is analyzed when a cascade controlled SEA is employed to display a virtual parallel spring-damper system. The case of a null desired impedance and of a pure spring are also tackled. The range of renderable mechanical impedance and guidelines for the selection of the control gains are derived.

In cyclic motions, e.g. during locomotion, part of total kinetic energy, which otherwise would be wasted during direction inversion, can be conveniently stored in elastic elements in order to be later reused. Such energy recovery strategy, which can be adopted in robotic systems to improve energetic autonomy, mimics biological solutions, where muscles, tendons and ligaments are exploited also as elastic energy buffers. The addition of compliant elements, in parallel or in series to conventional actuators, may result in complex assemblies. Conversely, compact solutions can be obtained if elasticity is embedded in the structure of the actuator. In this paper an electric rotary compliant actuator, integrating a magnetic non-linear torsion spring, is presented. The system is a parallel elastic actuator and it allows to efficiently produce oscillating motions, as needed in several biorobotic applications. The stator comprises mono-phase windings while the rotor includes permanent magnets in axial Halbach configuration. Additional magnets are advantageously located in the stator to embody the intrinsic parallel elasticity. A proof-of-concept prototype was developed, whose winding coils were designed based on magneto-static FEM simulations. The actuator was experimentally characterized and the present dynamic behavior was compared to the theoretical one calculated by considering a non-linear electro-mechanical model.

In complex dynamical tasks human motor control notably exploits the possibility of regulating joints mechanical impedance, both for stability and for energetic optimization purposes. These biomechanical findings should translate in design requirements for wearable robotics joints, which are required to produce adaptable intrinsic viscoelastic behaviors.

This paper describes the optimization of a planar wearable active orthosis for hip and knee assistance during overground walking. A non-anthropomorphic design is pursued in order to improve ergonomics and to reduce torque requirements. Based on a previously-developed systematic search algorithm of the admissible generalized solutions for the selected problem, a solution is selected and optimized by means of genetic algorithms and constrained non-linear optimization. The optimized design allows to conveniently redistribute mechanical power through different actuators, i.e. peak torque and velocity requirements for each actuator can be modulated, thus promoting a lighter design. A detailed analysis of the resulting mechanism workspace is carried out, including the evaluation of kinematic singularities, in order to verify the adequateness of the design in real-world scenarios. The developed model and optimization results are validated through a numerical analysis and experiments in a mock-up system.

This work proposes a mechatronic solution to increase the back-drivability of a state-of-the art robot for wrist neurorehabilitation. The final goal is to reduce robot mechanical impedance in order to cope with intrinsic kinematic constraints, which are adopted by the human brain to solve redundancy during pointing tasks with the wrist. The handle of the robot has been provided with a load cell and a direct force control scheme has been implemented to minimize the interaction forces/torques between the user and the robot. To this aim gravity, inertia and friction of the more proximal DOF of the robot (relative to Pronation/Supination (PS) movements) have been estimated and compensated for. The proposed solution resulted in a 70% reduction of the end-point perceived inertia in PS DOF as well as in a decrease of torques exerted by the user during both 1-DOF and 3-DOFs tasks. The average reduction of interaction torques is around 81% and 78% respectively. This work constitutes an important starting point for the analysis of the effect that different levels of robot transparency could have on the human neural constraints adopted during redundant tasks, such as pointing movements with the wrist.

In the design of wearable robots, the possibility of dynamically regulating the mechanical output impedance is crucial to achieve an efficient and safe human-robot interaction and to produce useful emergent dynamical behaviors. In this paper we propose a Variable Impedance Differential Actuator (VIDA) for wearable robotics applications. The system comprises two actuators (one being an impedance-controlled rotary Series Elastic Actuator) connected through a Harmonic Drive in a differential configuration used to separately control output position and mechanical impedance. Design choices regarding the overall architecture and the single components are presented and discussed. The mechanical structure also comprises a custom-made torsion spring designed after a CAD/FEM optimization. An electromechanical model of the system has been developed and a control strategy, based on the equilibrium point approach, is simulated to validate the performances of the system against system requirements. The actuation architecture allows to implement a control strategy where an equilibrium position and impedance field are simultaneously and independently regulated. This is possible still adopting very simple control laws: two controls for position and impedance regulation of the two input shafts.